Infrared laser catheter system

Abstract

Laser energy produced by a laser operating In the mid-infrared region (approximately 2 micrometers) Is delivered by an optical fiber in a catheter to a surgical site for biological tissue removal and repair. Disclosed laser sources which have an output wavelength in this region include: Holmium-doped Yttrium Aluminum Garnet (Ho:YAG), Holmium-doped Yttrium Lithium Fluoride (Ho:YLF), Erbium-doped YAG, Erbium-doped YLF and Thulium-doped YAG. For tissue removal, the lasers are operated with relatively long pulses at energy levels of approximately 1 joule per pulse. For tissue repair, the lasers are operated in a continuous wave mode at low power. Laser output energy is applied to a silica-based optical fiber which has been specially purified to reduce the hydroxyl-ion concentration to a low level. The catheter may be comprised of a single optical fiber or a plurality of optical fibers arranged to give overlapping output patterns for large area coverage.

What is claimed is:  
     
       1. A surgical system comprising: 
       a hollow elongate surgical instrument, having at least one lumen for receiving an optical fiber, and being maneuverable to provide a conduit for transmission of laser energy to a surgical site; and  
       a flexible, elongate fiber for conducting laser energy from a proximal end of said fiber to a surgical site at a distal end of said fiber, the proximal end for receiving laser energy, and said fiber being a silica fiber including means for reducing absorption of laser energy at a wavelength of about 1.4-2.2 micrometers.  
     
     
       2. The system of  claim 1 , wherein said fiber is suitable for coupling with and conducting energy of a Holmium-doped Yttrium-Aluminum-Garnet laser. 
     
     
       3. The system of  claim 1 , wherein said fiber is suitable for coupling with and conducting energy of a Erbium-doped Yttrium-Aluminum-Garnet laser. 
     
     
       4. The system of  claim 1 , wherein said fiber is suitable for coupling with conducting energy from a Thulium-doped Yttrium-Aluminum-Garnet laser. 
     
     
       5. The system of  claim 1 , wherein said fiber is suitable for coupling with and conducting energy from a Holmium-doped Yttrium-Lithium-Fluoride laser. 
     
     
       6. The system of  claim 1 , wherein said fiber is suitable for coupling with and conducting energy from a Erbium-doped Yttrium-Lithium-Fluoride laser. 
     
     
       7. The system of  claim 1 , wherein the said fiber is suitable for conducting pulsed laser energy. 
     
     
       8. The system of  claim 1 , wherein the said fiber is suitable for conducting pulsed wave laser energy sufficient to remove biological tissue by vaporization. 
     
     
       9. The system of  claim 1 , wherein said fiber is suitable for conducting laser energy with a pulse width of 0.2-5 milliseconds. 
     
     
       10. The system of  claim 1 , wherein said fiber is suitable for conducting pulsed laser energy at a repetition rate of about 1 to about 10 pulses per second. 
     
     
       11. The system of  claim 1 , wherein said fiber is suitable for delivery of energy to a surgical site of at least 0.57 millijoules per pulse. 
     
     
       12. The system of  claim 1  wherein the hollow elongate instrument is a catheter. 
     
     
       13. The system of  claim 1  wherein the fiber is suitable for conducting continuous wave radiation. 
     
     
       14. The system of  claim 13  wherein the fiber is suitable for to photocoagulate tissue.